Roasted Salmon Fillets with a Crusted Pecorino and Pesto Topping

This recipe, invented by my good friend Lin Cooper, started life under the grill, but now, in my attempt to more or less eliminate the grill, I'm happy to say that it cooks very happily and easily in a high oven.

One word of warning, though: it works much better with fresh pesto sauce from supermarkets than it does with the bottled kind.